42 Field Columbian Museum — Geology, Vol. II. 



to the base of the dorsal ramus, throughout the whole extent of the 

 concave portion of the border. The bone differs from the scapula 

 of Muranosaurus* in the less expanded ventral ramus, which is sepa- 

 rated from its mate by the clavicle and episternum. From the Crypto- 

 clidus\ scapula it differs in having a more slender and elongate dorsal 

 ramus, and in the non-expansion of the ventral ramus. From a 

 scapula of PL mudgei Crag, from the Lower Cretaceous in the 

 University of Kansas Museum, it differs in its much less slender 

 coracoidal and dorsal rami. The bone is also much more slender 

 than in Peloneustet. (See PI. XII.) 



The coracoid is a very large and broad plate, with a slender, 

 blade-like epicoracoid projection. Its glenoid portion is massive, 

 with a smaller humeral articular surface, and a larger scapular facet, 

 meeting each other in a very obtuse angle. The external border is 

 thickened and concave, produced into a considerable projection at 

 the posterior angle. Just before its termination there are several 

 tooth-like projections of small size, evidently for muscular attach- 

 ment. The posterior margin is thin, with rounded angles and a slight 

 concavity between them. Opposite the glenoid articulation the bone 

 is massive, meeting its fellow in a thickened bar with an oblique 

 sutural surface. Immediately posterior to this interglenoid thicken- 

 ing, the bone on the mesial side is very thin, and in the anterior part 

 of this thinned portion, near the middle line, there are two large, 

 well-defined, round foramina that have never before been described 

 in the coracoid, though perhaps indicated in the description of Trin- 

 acrotnerum. The clavicular or epicoracoid process in front is long 

 and thin, with nearly parallel sides, the anterior end slightly expanded 

 and its margin with a cartilaginous border. The sutural surface for 

 the clavicle extends back on the upper surface to nearly midway of 

 the process. The coraco-scapular foramen is elongate in shape and 

 is bounded entirely by the two bones, save for a short distance at the 

 front inner part where the clavicle completes the margin. The cora- 

 coid has the posterior outer angle more produced than in- either 

 Crxptoclidus, Peloneustes or Muranosaurus, and the clavicular process 

 is longer and better developed than has been described in any form, 

 except perhaps in Trinacromerum. 



The clavicle is a thin, concave, irregularly triangular or triradi- 

 ate bone, and is well developed. It lies upon the ventral plate of the 

 scapula and the epicoracoid process of the coracoid, and above the 

 squamous margin of the episternum, a remarkable position for a 



♦Andrews, Ann. M;ii;. Nat. His. xv, 43c. 

 t Andrews, Ann. Mag. Nat. Hist, xv, 35$. 



